The contributing areas 3d represent the real draining areas afferent to a point in the basin, not only its projection on the plane as the Tca do.
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<h3>Inputs</h3>
<ul>
<li>the file containing the matrix of pitless elevations (obtained with pitfiller)</li>
<li>the file containing the matrix of drainage directions (obtained with Markoutlets or DrainDir)</li>
</ul>
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<h3>Output</h3>
<ul>      
<li>the file containing the matrix of the real areas</li> 
</ul>
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<h3>Notes</h3>
The way to calculate the 3D area is to approximate with triangles the DEM surface and then summing the triangles area going downstream from sources to outlet. 